Using a canine animal model, two major questions concerning electromagnetic stimulation of bone healing in segmental cortical auto-grafts are addressed. These include: (1) Short term (two months) potentiation of remodeling of autograft material with concomitant changes in strength and (2) Long term stimulation (six months) effect on further consolidation or remodeling of autografts. This change of autogenesis on bone graft properties will be assessed using bi-weekly roentgenographs, biomechanical testing to failure of the transplant regions after excision, and evaluation of the cummulative new bone formation and porosity using continuous tetracycline labeling and microradiography. Also to be considered is the observed incidence of graft failure as characterized by fatigue fractures and the non-union rate with electromagnetic stimulation as compared to non-stimulated controls.